Method of making air filtering material



Dec. 9, 1941. D. E. HENNESSY 2,265,370"

METHOD OF MAKING AIR FILTERING MATERIAL Origihal Filed Nov. 18, 1939 Z4 Z3 Z4 73 Y Z3 Z3 Z5 'i v INVENTOR 24, 24

17mm"; Eflm msr 4m ATTORNEYS Patented Dec. 9, 1941 METHOD OF MAKING AIR FILTERING MATERIAL Daniel E. Hennessy, Leominster, Mass., assignor to Springfield Wire & Tinsel 00., West Springfield, Mass, a corporation of Massachusetts Original application November 18, 1939, Serial N 0.

1940, Serial N0. 346,641

7 Claims.

pad of curled or shredded metallic wool coated with an oily substance for the purpose of retaining dust particles which may be carried by the air flowing through it. It has been found in practice that the oily substance has a tendency to drain oil, particularly under warm conditions; and it is one object of the invention to improve the quality of the metallic material so that oil will be retained permanently throughout the entire body of the mat and will be distributed automatically as needed. A further object of the invention is to provide an improved method by which this improved material may be made in a continuous operation. Additional advantages and objects of the invention will appear from the following description and claims.

This application is a division of my prior application Serial No. 305,092, filed November 18, 1939.

Referring to the drawing:

Fig. 1 is a diagrammatic view showing one manner of making the improved product;

Fig. 2 is an end view, on an enlarged scale, of the product shown in Fig. 1;

Fig. 3 is a detail, on a greatly enlarged scale, of an intermediate product;

Fig. 4 is a detail, on an enlarged scale, on line 4-4 of Fig. 1;

Fig. 5 is a detail of a modified method of wind- 1 Fig. 6 is an end view, on an enlarged scale, of the structure shown in Fig. 5;

Fig. 7 is a plan view of the improved product on a greatly enlarged scale; and

Fig. 8 is a side elevation of the product shown in Fig. 7.

Before discussing the preferred method by which the product is obtained the ribbon-like material which forms the basis of the final mat will be considered. It has hitherto been proposed to impart corrugations of various forms to a wire in order to prevent undesirable compacting of the product when matted together. These corrugations, however, have not had the necessary property of assisting in the retention of oil. The product shown in Figs. 7 and 8 is made of fiat wire, preferably copper or bronze only a few Divided and this application July 20,

thousandths of an inch in thickness, having kinks or contracted bights at intervals along its length. The size of the wire has been exaggerated greatly in these figures to permit illustration. The product shown can best be conceived as being made by looping the flat wire and pulling the loops tight. The contracted bights or kinks thus formed serve as capillary pockets for the retention of oil. If a mat or pad formed of this material be sprayed with or immersed in oil and the excess drained 01f, there will be a small drop of oil held by capillary attraction in each of the kinks. Furthermore, the effect of the oil will not be confined to the kink itself as the oil will tend to spread over the wire and maintain an oily film upon the fiat surfaces of the Wire on each side of each kink.

While the nature of the product is best shown by conceiving it as having been made by the simple process described, a faster method is required in practice. I have shown diagrammatically in Fig. 1 a more rapid and economical method by which the product may be made as a continuous operation. In this figure, ll) represents a needle or mandrel held against rotation and of any desired cross-sectional form. Around this mandrel the wire II is carried by a fiyer or guide l2 whichrotates around the mandrel at high speed, drawing the wire from a spool l3 which is mounted to rotate under a frictional drag. This form of device is standard equipment for making helices of thin wire and for forming gimp or tinsel products, and need not be described in detail. One suitable construction will be found in the Montgomery and Mason Patent 1,386,350, dated August 2, 1921.

The heel of the needle is rounded as at hi and, as the material is wound, this heel forces the wound material to slide longitudinally off the end of the mandrel in the form of a nonrotating helix. If the mandrel is of square or triangular cross-section the engagement of the corners of the mandrel with the wire will be sufficient to prevent the helix from slipping around, but if the mandrel is round it may be necessary to press a pad or roller against it as indicated at I5 and as shown in the French patent to Martin 57,945, March 13, 1863. The same result may be accomplished by holding the finger lightly against the side of the mandrel, the formed helix sliding off the mandrel underneath it. The product in this form would have somewhat the appearance indicated at H5 in Fig. 3, except that the wire is constantly being drawn better be said that the helix is passed between the spaced surfaces without permitting its internal rotation; the rotation which is to btlsilppl'ssed being relative only to the normal condition of the helix. The preferred form of device for What I claim is:

1. A method of making air filtering or sound absorbing material which comprises forming a fiat metallic ribbon into a helix, and extending the helix without internal rotation an amount suflicient tocause the formation of kinks and to impart'a permanent set'to' the wire inthe kinked portions.

2. A method of making air filtering or sound absorbing material which comprises forming a hat m'etallicribbon into a helix, progressively drawing out the helix, restraining the helix withstretching out the helix is ,iridioatediri Figs; ..1-'

and 4. The helix is initially led through a guide 20 underneath a bar 2| andover a bar 2 2, and the speed of the windup H is so regulate'd-that the helix will be almost completely-stretched out on leaving the bar 22. This manner of passing the helix around the bar 22 keeps it frominte'r'nal,

rotation and causesthe loops which. form the hel-ixto be drawn out into contractedbights 23 as indicated in-Figsi'l and 8; It will be "b served-that the 'standing 'p'art's' 24 'of the flat wire on -eitherside of each" kink are "laterally ofiset fromeach'other; thisbeing best shown in Fig. 7'.

The resulting product may -be-merely tangled together to form a -pad--'or"mat,- but itis preferred to oross wind it into aself-sustaining mass, For this purpose a traverse""mechanism indicated generically by 25 is interposed betweenthe' bar 22 and-the Winding form-1 'iand is preferably reciprocated at a rate rather 'high'with relation to the speed'of' the wi-ndupso that the strandis caused to travel from-one end of the path-of-reciproca tion of the traverse guide to the other at a 'con; siderable angle; The-winding form 1 7' may be in the form of a roundor flat mandr'el,--itbei-nggen: erally desirable to have it fla't.--In the case shown the product will beformed as itself-sustaming flattened mass-26, Fig; 2; ofdefinite length, which-maybe removed-from themandrel after-the desired thickness has been-built up." If desired; the wound wi-re may be-iedprogressively off-the mandrel as-by mechariism describedin my copending application, Serial -'N 0'. 307,312, ii-led- December 5, 19394130 form a continuous, selfsus tainingrope-like product.- a a a 7 As a 'furtherrefinement the material -maybe cross wound directly upon apiece of screening 21:, Figs. and fi, the-latterfigure showing-the strand as .having b'eenbuilt up by cross winding cross windingv isused,

out relative rotation between the part so restrained and the part being drawn out to cause the, formation of'kinks, and imparting a permanent set to the ribbon in the kinked portions So formed." 3.'A method'otmaking air filtering or sound absorbing material which comprises forming a flat..i'n"etallic ribbon into a helix, and straightening out the helix bytdrawing it in a reversely curved path under sufficientftension to form kinks in' theribbon andt'o imbaita permanent set to the wire in its kinked portions.

4..A methodof making air filtering 'orjso'und absorbing "material which comprises 'fo'rmingg'a fiat metallic ribbon into a'helix; andiforming spaced kinks by elongating 'thebhelixii'rito sub stantially ribbon =form Without substantial -.internal rotation of .the helix'ahd under sufficleht stress to impart a p'ermarientset to th"e .ribbon,iii

its kinked portions. v

5. A "method fof making air .filtjerin'g or sound absorbing material iwhi'cliij comprises forming Q a fiat metallic ri'bbonintota helixpformijng spaced kinks-by elongating the helix without'fsubstam tial internal rotation ofith'e. helix -and:under Sui-i ficient tension to impart a permanent setto the ribbons in its 'kinked portions',.ahdcro'ss 'windt ing the resulting "product;

' A method" of making lair 'filtering :ors'oun'd absorbing materi'ahwhich "comprises Winding ,a fiat wire-about "a 'stationary'mandrel to' formia helix and drawing the helix directly'from'f the, mandrel between close-ly'spac'ed :surfaces to, ex tend the helix and "producej'a tkinked "ribboh' jlike product. t

7. A method of making air filtering or sound absorbing material which'comprises"winding a fiat wiraabouta 'stationar'yjmandrelito form a helix, drawing the hel-ixdireotlyirom the man-' drel'between closely spaced surfaces to extend the. helix and produce a *kihkedribbonslike. product, and-cross winding the-ribbonfto; forni amat;

' DANIEIJZEZfHENNESSYl 

